Summary: High-resolution record of Northern
Hemisphere climate extending into the
last interglacial period
North Greenland Ice Core Project members*
*A full list of authors appears at the end of this paper
...........................................................................................................................................................................................................................
Two deep ice cores from central Greenland, drilled in the 1990s, have played a key role in climate reconstructions of the Northern
Hemisphere, but the oldest sections of the cores were disturbed in chronology owing to ice folding near the bedrock. Here we
present an undisturbed climate record from a North Greenland ice core, which extends back to 123,000 years before the present,
within the last interglacial period. The oxygen isotopes in the ice imply that climate was stable during the last interglacial period,
with temperatures 5 8C warmer than today. We find unexpectedly large temperature differences between our new record from
northern Greenland and the undisturbed sections of the cores from central Greenland, suggesting that the extent of ice in the
Northern Hemisphere modulated the latitudinal temperature gradients in Greenland. This record shows a slow decline in
temperatures that marked the initiation of the last glacial period. Our record reveals a hitherto unrecognized warm period initiated
by an abrupt climate warming about 115,000 years ago, before glacial conditions were fully developed. This event does not appear
to have an immediate Antarctic counterpart, suggesting that the climate see-saw between the hemispheres (which dominated the
last glacial period) was not operating at this time.
The two deep ice cores drilled at the beginning of the 1990s in
central Greenland (GRIP1­3
and GISP24,5